The rising world population and diminishing areas for cultivation mean that there is a need for sustainable production. Genomic information may be exploited in this context for the optimization of production processes, in partricular in chemistry, in the production of foodstuffs and in agriculture. Today, enormous amounts of genomic information are available. However, this predominantly takes the form of sequence information with indirect functional assignment, if any.
It has already been attempted to express individual genes from various organisms in plants for a variety of purposes. In these experiments, it was attempted to study the function of a particular gene in the plant and its effect on the physiology of the plant.
Approaches regarding the expression of a plurality of genes of a specific donor organism in a model plant have as yet only been limited to transient expression systems. Such an approach is described, for example, in WO 99/36516 and WO 01/07600, where a cDNA library derived from the donor organism is inserted into a suitable vector of a plant virus, whereby rapid and strong expression of the cDNA can be achieved after infecting the host plant with said vector. However, only those cDNAs which exist in the original library can be expressed in the plants, but significant amounts of the genes of a genome are expressed only very weakly or under highly specific conditions, if at all, and therefore not covered by such an approach. Another disadvantage of this procedure is that the infection causes effects. These effects may influence the results of physiological studies on the infected plants. Another weakness, which is likewise inherent in transient expression, is that the availability of the transfected material is only transient. Thus, the periods available for analytical studies are only relatively short, while developmental and prolonged effects are not identified. Moreover, when viral vectors are used, the size of the sequences which can be incorporated is limited owing to the fact that the sequences must be packaged in the viral coat.